Zack: The way it NORMALLY used to work, before we got car companies obsessed with better corproate fuel mileage, was:
The numerically higher the gearing, the quicker the acceleration but the lower the top speed. So, 4.11 would be quicker but slower than 3.73, and 4.56 would be quicker but slower than both the 4.11 and 3.73. This worked well when car companies geared cars for maximum speed rather than for fuel mileage.
However, once the car companies started to gear for fuel mileage, this rule fell apart, as they then always gear way numerically low in order to keep the highway rpm very low, which improves gas mileage a VERY small amount, but reduces the acceleration capabilities a LOT. This is why a Corvette pulls only 1500 rpm at 60 mph, and has almost no acceleration capability at that speed in 6th - it has to be downshifted to accelerate.
Horsepower required to move a car down the highway is directly proportional to the aerodynamic shape/size of the vehicle, but rises with the CUBE of the speed. ie. going twice as fast requires 8 times as much power. The top speed of a vehicle is determined by how the shape of the engine power curve interacts with the air drag caused by high speed.
For maximized speed, you have to gear the vehicle so that the point in the power curve where peak horsepower occurs coincides exactly with the speed to which that power should be able to push that specific vehicle (based mostly on its coefficient of drag and slightly on its weight). If the engine peaks "lower" or "higher" than that specific speed, your top speed will be reduced. gearing for best gas mileage is NOT consistent with gearing for best top speed.
When a vehicle is geared for mileage versus top speed, you do NOT in general lose top speed when you regear to a numerically higher ratio. Instead, you often GAIN top speed.
In the case of the stock SSR, if you put on proper speed rated tires and remove the speed restiction in the computer that is based on the speed rating for the stock tires, but leave the gearing stock, it will go about 144 mph.
The computer says that my own SSR will likely do, under the same unrestricted conditions, about 154 mph, because of the combination of BOTH better gearing and more power due to the headers, exhaust, and dyno tune.
Jim G
